Banu Musa Memories Of Forgotten Genius

About 850, three brothers Jafar Muhammad ibn Musa ibn Shakir, Ahmad ibn Musa ibn Shakir and al-Hasan ibn Musa ibn Shakir known collectively as Banu Musa wrote the Book of Ingenious Devices in Baghdad.  Few figures in Islamic scientific history are more colorful or intriguing than these three brothers and although their works in different scientific areas are attributed to them jointly, they did have their own areas of expertise.  Muhammad was mainly a specialist in geometry and astronomy, while Ahmad worked mainly on mechanics and al-Hasan excelled mainly in geometry.  The book contained descriptions of a hundred devices, most of which are trick vessels which exhibit a bewildering variety of effects.

The book described a total of 100 devices and how to use them.  It was based partly on the work of Heron of Alexandria and Philon of Byzantium, other ancient texts and it also contained original work by the brothers.  The book provides the first examples of various mechanic elements like the use of crankshafts, and it includes technical drawings, logic and command systems and it is especially noted for its automatically controlled systems.  The Banu Musa designed fountains that change shape by the minute, clocks with all kinds of little gimmicks, trick jugs, flutes that play by themselves, water jugs that serve drinks automatically, a full-size mechanical tea girl that actually serves tea, and a dredging machine designed to salvage submerged objects from the bottom of rivers and seas.  The flute sounds were produced through hot steam and the user could adjust the device to various patterns, so that they could get different sounds from it, and this device is viewed as the first automatic machine.  Some of their inventions include explanations on a variety of valves, siphons and floats, water wheels, a feedback controller, a programmable machine and the means by which they created their stunning effects are of great significance for the history of engineering.

Their most famous invention was a magnificent artificial tree with gold and silver branches.  The brothers filled each branch with multicolored leaves that seemed to sway in the wind and artificial birds that fluttered their wings and sang.  One device that they built, had a single outlet pipe in a vessel which might pour out first wine, then water and finally a mixture of the two.  The Banu Musa used conical valves as ‘in-line’ components in flow systems, the first known use of conical valves as automatic controllers.  An almost constant head was maintained in a float chamber by feedback control.

The book describes the construction of various automatic fountains, in one of these the water issues from the fountainhead in the shape of a shield, or like a lily-of-the-valley, with the shapes being discharged alternately as either a sheet of water concave downwards, or a spray.  Another fountain discharges a shield or a single jet, while a variation of this features double-action alternation, that has two fountainheads, with one discharging a single jet and the other a shield, and the two alternating repeatedly.  Another variation features one main fountainhead and two or more subsidiary ones, such that when the main one ejects a single jet, the subsidiaries eject shields, with the two alternating.

This book also describes a dispenser for hot and cold water, where the two outlets alternate, one discharging cold water and the other hot, then vice versa repeatedly.  It also describes a vessel with a basin by its side where, when cold water is poured into the top of the vessel, it discharges from the mouth of a figure into the basin; when hot water or another liquid is poured into the basin, the same quantity of cold water is discharged from the mouth of the figure.  A boiler with a tap to access hot water is also described.  The water is heated through cold water being poured into a pipe which leads to a tank at the bottom of the boiler, where the water is heated with fire.  A person can then access hot water from the boiler through a tap.

Although most of their inventions are considered to be just toys for entertainment and amusement, the effort that the Banu Musa put into their impressive gimmicks was spectacular, as was their ground-breaking technology utilizing water under pressure in the in the area of engineering known as automation. By making clever use of one- or two-way self-closing and opening valves, their devices were able to delay action and respond to feedback, and establish On-Off control using upper and lower limits.  They created simple mechanical memories for their automatic systems, which became in principle our first modem machines that are not too different from the machines we have today and they still astonish people.  They mainly used water under pressure for control rather than the electronics of today, but many of the operating principles are still the same.

Written for Linda G Hill Life in progress January 5, 2018 #JusJoJan Daily Prompt is Memories suggested by Cage Dunn.

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